Serial thrombolysis-related changes after thrombolytic therapy with tPA in patients with acute myocardial infarction

THROMBOSIS RESEARCH 58; 331-341,199O 0049-3848/90 $3.00 + .OOPrinted in the USA. Copyright (c) 1990 Pergamon Press plc. All rights reserved.

SERIAL

THROMBOLYSIS-RELATED CHANGES AFTER THROMBOLYTIC THERAPY WITH TPA IN PATIENTS WITH ACUTE MYOCARDIAL INFARCTION

Chao-Hung Ho, and Shih-Pu Wang1 Division of Hematology & Cardiologyl, Department of Internal Medicine, Veterans General Hospital, Taipei, Taiwan, R.O.C. (Received 21 .ll .1989; accepted in revised form 16.1 .1990 by Editor S. Okamoto) (Received by the Executive Editorial Office 26.2.1990)

ABSTRACT Twenty-nine patients with acute myocardial infarction were given recombinant tissue plasminogen activator 6 hr after onset of chest pain (mean: 3.2 (tPA) within hr 1 with a total dose of 100mg iv drip given within 3hr for thrombolytic therapy. Serial determinations of total FDP, FDP D-Dimer (specific for FbDP), fibrinoreptilase time (RT), plasminogen, APTT, gen (Fg), PT, alpha2-antiplasmin (AAP), euglobulin lysis time (ELT) and and antithrombin III (ATIII) were performed before initiation of tPA 1, 2, 4, 6, 12, 24, 48 hr after injection in the 29 patients in order to evaluate the hemostatic changes after thrombolytic therapy. Decreases & ELT were found from 1 hr after of plasminogen,Fg,AAP therapy and persisted to 24,12,24 & 12 hr, respectively, with the maximum decrease usually between l-4 hr. Increfound from ases of FDP, FDP D-dimer, PT, APTT &'RT were I, 1, 2, 1 & 1 hr after therapy, respectively, and suswith tained to 24, 12, 12, 24 & 12 hr, respectively, maximum increases between l-4 hr. No significant changes 4 of of AT111 were noted during the 4a-hr study-period. these 29 patients (13.79%) had the complication of loof packed 1 unit calized bleeding, 1 of them needed transfusion. All thrombolysis-related red blood cell within recovered 24 hr after tPA therapy. No changes parameter we have studied so far could be used for the of the possibility of coronary patency after prediction

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Thrombolytic words: Key activator infusion, acute related changes

therapy, myocardial

331

tissue-type infarction,

plasminogen thrombolysis-

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But markedly elevated FDP was found to be tPA therapy. associated with high risk of bleeding complication. As for 24 hr or longer, the coagulation changes persist tests and close careful monitoring of the coagulation observation of clinical bleeding signs up to 48 hr are necessary in patients treated with tPA.

INTRODUCTION Recombinant human tissue-type plasminogen activator (tPA) thrombolysis in has been introduced recently for coronary patients with acute myocardial infarction with satisfactory thrombolytic effects (l-5). Originally when tPA was developed and first used clinically, it was thought to be a fibrin-specific agent with little systemic fibrinolytic effect (1, 6-9). However, as more studies have been made, significant decreases of plasma fibrinogen,plasminogen and alpha2-antiplasmin (AAP) have been found during tPA infusion, especially when the dosage of tPA was high and the infusion period was long (10,ll). Although this fact was recognized, large and complete studies to demonstrate the during thrombolysis-related changes before, and after tPA infusion were few (12-14). We undertook the present study to detect the serial changes of the most important thrombolysisrelated parameters after tPA therapy in patients with acute myocardial infarction and to evaluate the systemic fibrinolytic effects and their clinical significance. MATERIALS ANJ METHODS Patients Twenty-nine patients referred from the emergency unit within 6 hours from the onset of chest pain of a suspected first myocardial infarction entered into our study. All patients met the following criteria:(a) age < 75 years: (b) chest pain for at least 30 minutes and not relieved by nitroglycerin: (c) ST elevation > 0.2 mv in at least 2 leads; (d) no bleeding tendency,no coexisting valvular disease and no contraindication to thrombolytic therapy;(e) they all consented to our study plan. Treatment

regimens

All patients entered into the study were first given iv bolus of 5000 i.u. heparin, followed by 100 mg tPA administration (Boehringer Ingelheim, West Germany ) over 3 hr. An iv bolus of 10 mg tPA was followed by 50 mg iv during 1 hour and 40 mg iv during two hours. If no clinical bleeding was noted, continuous iv infusion of heparin was then given with a daily dosage 20000 i.u. for l-2 days. Catheterization was carried out 3 hours after initiation tPA infusion in all the patients to confirm the patency coronary artery.

of of

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Collection

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of samples

Blood samples were obtained for detecting fibrin(ogen) degradation product (FDP), FDP D-dimer, fibrinogen, prothrombin time (PT), activated partial thromboplastin time (APTT), reptilase time ( RT ), plasminogen, AAP, euglobulin lysis time (ELT) and antithrombin III (ATIII) before and 1, 2, 4, 6, 12, 24 and 48 hours after initiation of tPA administration. Blood samples were taken by specially trained technicians. For measurement of the parameters above, except FDP, 4.5 ml blood was collected in 0.5 ml sodium citrate, and immediately centrifuged at 1400 g. The plasma was then transferred to polystyrene test tubes and stored at -70' C until assayed. For measuring FDP, only serum was needed. Fibrinogen levels were determined by a clotting rate assay of Clauss (15). Heparin interference is minimized by lo-fold D-dimer dilution of the sample in the clotting rate assay. FDP was detected by a semi-quantitative determination of the fibrin degradation product D.D. in titrated plasma by latex agglutination (D-Di Test, Diagnostica Stago, France). The latex particles used for this assay were sensitized with mouse monoclonal antibodies which do not react with fibrinogen. Plasminogen was assayed by an amidolytic method (16) with the synthetic chromogenic substrate CBS 30.41 (Stachrom Plg, Diagnostica Stago, France). Results were expressed as percentages of normal values by comparison with values from a standard curve generated with pooled, normal human plasma. AAP level was also measured by the amidolytic procedure (17) using a new specific ( Stachrom antiplasmin, CBS 33.08 chromogenic substrate Diagnostica Stago, France) for plasmin and with added plasmin. Reductions of the amidolysis induced by the added plasmin as a result of AAP in the sample were expressed in terms of the percentage of normal AAP activity by comparing results with those obtained with corresponding dilutions of pooled, normal human plasma. AT111 was detected also by the amidolytic method (18) with a ( Stachrom ATIII, substrate CBS 34.47 synthetic peptide Diagnostica Stago, France ). Incubation of plasma in the presence of heparin with an excess of thrombin was first performed, the remaining amount of thrombin is determined by its amidolytic activity on the chromogenic substrate. The levels of AT111 Were activity AT111 expressed in terms of the percentage of normal obtained with a corresponding with those comparing results by dilution of pooled, normal human plasma. ( Using the serum, FDP was measured by latex agglutination Spli-Prest, Diagnostica Stago,France ). PT, APTT, RT and ELT were by the conventional coagulation tests. The thrombomeasured plastin used for detecting PT had an anti-heparin function (Neoplastine (PT), Diagnostica Stago, France) to eliminate the influence of heparin.

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Using an automated hematology analyzer ( Sysmex M2000, Toa Medical Electronics Co., Ltd. Kobe, Japan), complete blood counts in relation to tPA were performed at 0, 24, and 48 hours injection. T-test was used to compare all the changes before and after tPA infusion in order to find the statistical significance. RESULTS Twenty-nine patients were studied, of them 28 were men and 1 was a woman. Their mean age was 58.4 years, ranging from 44 to 68 years. The mean time from onset of chest pain to tPA injection was 193.7 minutes (SD 57.9). The mean time from onset of chest pain to catheterization was 391 + 90 min. The patency rate of (26 out infarct related vessels was found to be as high as 89.7% (27 out of 29 who had > of 29 who had ~100% stenosis) to 93.1% grade 1 antegrade flow) in this study, when catheterization was performed about 3 hours after initiation of tPA infusion. Chancres of the thrombolvsis-related

parameters

All 29 patients injected with tPA had a decrease of the plasminogen, fibrinogen and AAP (Figs l-2). This appeared usually

100%

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Before

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t After’

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12

24

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48Hrs

infusion

FIG. 1 Mean changes of ATIII, plasminogen and AAP in 29 patients before and after tPA infusion

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300__60

,oo

AFTER tPA IN AMI

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cm..

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*-_* ‘-.... *...._ --__--.*__ ____APTT .___.__R_eptilase Ti~~k’..‘.“~.‘....-‘ ~.~~~~~--.~~~~~~~~~~_~ -.----_--__,_-_-_-__-----w-w--.

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6

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changes of fibrinogen, APTT and RT before and after tPA infusion

FIG. 2 Mean FDP (us/m

infusion

I)

in 29 patients

FDP, D-dimer (*19/m 0 ELT (hrs)

400 -- 8

I 48 Hrs

tPA

infusion

FIG. _3 Mean changes of euglobulin lysis time, FDP ant FDP D-dimer in 29 patients before and after tPA infuslon

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within an hour after tPA infusion, and persisted to 24, 12 and 24 hours respectively, with the maximum decrease usually between 1-4 hours. Plasminogen, fibrinogen and AAP levels declined up to 22.80 + 24.67% of baseline, 43.82 + 24.50%, 59.72 + 18.76% and respectively (p values all O.O5, paired t-test). All thrombolysisrelated changes recovered at 24 hours after tPA therapy. Complete blood count, serum CPK and clinical comolications All items of the complete blood count were found decreased 48 hours after tPA infusion (Table l), but only Hb, rbc count and platelet count were significantly decreased (p=O.O02, 0.008 and 0.01, respectively). Serum CPK was found to be increased and gradually returned to be normal 72 hr after tPA infusion (Table of the 29 patients had the complication of localized 2). Four bleeding, one of them needed 1 unit of packed red cell transfusion. All the bleeding episodes could be well controlled clinically, no any intracranial hemorrhage was noted.

TABLE 1 Hematologic

Changes After tPA Infusion

__-_-_-_-___-_-_____~-~~~-~----~-~-~~~-~~~~-~-~-~~~~~~~~~~~~~~~--

0 hour

24 hours

48 hours

t-test (p value) _______-________-_--~~~~~~~~~~-~~~~~~~~~~~-~~~-~~~~~~~~~-~~~-~~~RBC (M/ul) 4.47+0.66 4.13+0.45 3.92+0.49 0.008 WBC (/ul) 11760+4326 10684+2561 10311+2596 0.2 13.79+2.01 12.24+1.76 11.89+1.54 0.002 Hb (gm/dl) Hct (%) 40.39+6.64 38.22+6.94 37.29+8.04 0.2 Platelet (/ul) 306857+143381 227937+94206 185333+81956 0.01 _--_____-_-_________~~~~~--~~-~-~~~~~~~-~~----~-~~~~~~~~~~~-~-~-~ *Unpaired t-test for 0 hr verse 48 hr

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TABLE 2 Serum CPK Changes After tPA Infusion -___-_-_------_-_-_--_-~-__~~~_-~~_---__--~_--___-~__--___-______ 0 hr lhr 2 hr 4 hr 6hr 12 hr 24 hr 48 hr 72 hr --_---_--_--_---_--_-__--__--~_--~__--__--__--___-~_---__--__--__ Mean (u/l) 145.8 486.0 1032.8 1883.4 2385.5 2075.5 1316.8 510.4 261.2

SD 105.3 485.4 965.0 1532.9 1806.0 1257.5 911.1 511.3 206.1 ---_-----_--_-_-_-_-~-~-~---~---~------~---~---~--~-~~~~~~~~~~~~~

Comparison of the groups with QL? without and with orwithout coronary natencv

bleedinq

complication

Only 4 of 29 patients had bleeding complications. None of them had intracranial hemorrhage. In comparison with the maximum mean changes of all the thrombolysis-related parameters in these two groups, we found that the maximum mean increase of FDP was significantly greater in the group with complication than that in the group without complication (p =0.0003, unpaired t-test) (Table 3). On the other hand, of 29 patients, 26 had coronary In comparison with the maximum mean patency whereas 3 had not. changes of all the thrombolysis-related parameters in these 2 could not find any significant differences in any groups, we one of the parameters (p > 0.05). TABLE 3. Comparison of The Maximum Increases of Mean FDP in 2 Groups With or Without Bleeding Complication __-_--___--________-________________-~_----__-___-__--~--~---~--~ No of patient maximum increase Bleeding complication Group of FDP (ug/ml) _-___--_---________-____________-___-~_~---_--__-~~--~--~~~-~~~~No 372.61 1 25 Yes 4 960.00 2 _-----_-_-_____-_---~-__~__--_-~~---~-~-~~~--~---~~-~~~~~~~~~~-~~ p = 0.0003 I unpaired t-test DISCUSSION (tPA) is a widely used Tissue-type plasminogen activator thrombolytic agent, which has been widely used clinically in the last five years, especially in patients with acute myocardial infraction. It is a glycoprotein with a molecular weight of 70,000, which may be produced by recombinant DNA technology (19). that tPA had fibrin-specific properties Initially it was thought due to its direct affinity for fibrin (20). The potential for fibrin specificity has been verified in vitro (21) and in animal studies (22). Nevertheless, there is a limit to fibrin

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specificity of WA, Sobel and colleagues (23) pointed out that "large sustained doses of tPA are capable of overwhelming the low affinity of tPA for circulating plasminogen and hence of eliciting systemic fibrinogenolysis." As the dose and treatment duration of tPA were steadily increased to obtain an optimal regimen for dissolving coronary artery thrombi, the threshold for development of fibrinogen degradation (the lytic state) was exceeded. Thus, while relative fibrin specificity is indeed a used regularly characteristic of tPA, the dosage currently produces a lytic state in virtually all treated patients. As more clinical experiences are obtained, tPA is now found to be non-allergic and to have an excellent therapeutic effect in opening thrombus-occluded coronary arteries. The patency rate of the infarct-related vessels was found to be as high as 89.793.1% in our study. The reasons of the higher patency rate in our study are probably due to 1) the rather late catheterization time (about 3 hr after tPA infusion) which in most patients gave enough time for the dissolution of the thrombus, and 2) the spontaneous recanalization occurring during the whole course in addition to the effect of tPA infusion. Thus, the patency rate should be smaller than our calculation values. recommended In our study, which used the internationally dose schedule of tPA from this manufacturer (Boehringer on license from Genentech) a considerable degree of systemic fibrinogenolysis was observed. Nevertheless, the incidence of bleeding complications was not high. Plasminogen, fibrinogen and AAP all decreased, which indicates excessive systemic plasminogen activator effect, this causes the formation of free plasmin, which then degrades fibrinogen with FDP formation. On the other hand, as plasmin increases, formation of plasmin-AAP complex occurs, thus causing a marked decrease of AAP. after tPA injection The increase of FDP D-dimer indicates localized thrombolysis as D-dimer represents exclusively the fibrin degradation product and not the fibrinogen degradation product. This is effective in treating the patients and represents the lysis of fibrin in the thrombus or hemostatic plugs (if present). On the other hand,the increase of FDP indicates systemic fibrinolysis and this means that at higher dosage of tPA, absolute fibrin-specificity is not achieved. The marked shortening of ELT in our evidence of the systemic active clot-lysis injection.

study is capacity

further of tPA

Though the fibrinogen level dropped down up to 59.72% of baseline, and prolongations of APTT, PT, RT were noted, the clinical bleeding rate was not high and could be tolerated. The explanation of this rather low bleeding rate may be that changes in blood coagulation factor activity are not sufficient to initiate a hemorrhagic episode from otherwise normal tissues and vasculature. Instead, bleeding complications of thrombolytic therapy appear to be the result of accelerated hemostatic plug

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dissolution, intervening in the physiologic hemostasis process which is beneficial to the body. Once the integrity of the vascular tree is compromised systemic fibrinolysis and antithrombotic therapy may further enhance the bleeding risk. In the group with bleeding complications, FDP was found to be markedly elevated (3428.57% of baseline in comparison with 530.34% of baseline in the group without bleeding complications). Although the sample size was not great in our study, this result is compatible with the finding reported by Rao et al and Mueller et al that at least following tPA therapy the levels of FDP correlated with bleeding complications (13-14). As the coagulation changes persisted for 24 hours, in order to predict bleeding complications it might be useful to follow FDP for up to 24 hours to identify patients with increased bleeding risk after tPA infusion. In such patients adequate clinical management might be particularly important to optimize the clinical benefits of tPA therapy. We can probably periodically perform the FDP assays over a 24-hr period. If FDP levels increase greatly, we should be aware of the high possibility of bleeding complication and try utmost to prevent this from occurring, such as by careful monitoring of the coagulation tests, close observation of clinical bleeding signs, avoiding any unnecessary venous or arterial puncture and other suitable methods of management. Proper management to prevent complication of bleeding can no doubt assure the therapeutic of thrombolytic therapy with tPA, making the success rate effect higher. ACKNOWLEDGMENTS This study was supported by grants (NSC 77-0412-B075-55) from the National Science Council, Republic of china. REFERENCES 1. COLLEN, D., TOPOL, E.J., TIEFENBRUNN, A.J., GOLD, H.K., WEISFELDT, M.L., SOBEL, B.E., KEINBACH, R.C., BRINKER, J.A., LUDBROOK, P.A., YASUDA, I., BUKLLEY, B.H., ROBISON, A.K., HUTTER, A.M., BELL, W.R., SPADARO, J.J., KHAW, B.A. and GROSSBARD, E.B. human tissue-type recombinant Coronary thrombolysis with randomized placeboa prospective, plasminogen activator: controlled trial. Circulati_o_n, 7-3, 1012-1017, 1984. Group. The thrombolysis in myocardial 2. TIM1 Study (TIMI) trial. N Enql J M_ed, 3-l-l,932-936, 1985.

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clot